Struggling with insulated consumer units and information on power dissipation

Hi Gary. I’ve always considered remote or detached garages exempt from regulation 421.1.201

-Andy

It is unfortunate that BS 7671 defines neither "domestic" nor "household". However, I suggest that it is distinct from commercial or industrial. I have no doubt that my detached garage is on my premises. If it were not, on whose premises would it lie?

OED: premises = "A house or building together with its grounds, outhouses, etc."

I'm not sure that applying additional seals to pre manufactured enclosure is a practical way forward - any modifications that aren't approved by the manufacturer would undermine the BS EN 61439 approval provided by the original manufacturer - leaving the installer with the onerous task of having to demonstrate compliance with all the requirements of the equipment standard. Even on a more practical level, as but one example, the front flap would likely need some means of latching to provide compression on any seal - so you'd have to make sure that any fixings you used for the new catch didn't affect the creepage and clearance distances within the enclosure (which would be difficult to achieve without manufacturer specific information that's not generally available), and also didn't damage any original corrosion protection (e.g. galvanising).  I suppose you could enclose the whole CU in an another airtight enclosure, but even that approach isn't without problems - one that was closely fitting would restrict heat dissipation (one of the OP's original concerns), but making it larger would mean that a much larger volume of moisture holding air would be trapped, itself increasing the condensation risk.

BTW I couldn't help noticing some of your responses seem to show the hallmarks of being AI generated - which AI engine are you using?

   - Andy.

I must emphasize that the electrical interconnection between the garage and the main house brings the garage under the same regulatory requirements as the domestic premises.

That's a very interesting claim - how do you come to that conclusion? Where in BS 7671 is that statement made? I'm curious as that principle, if true, would seem to have wide ranging implications as practically all premises in the UK are electrically interconnected via the National Grid.

   - Andy.

Hi Andy,

Best regards,

Gary Robert Jone JIB registered Electrician, Grade Technician

It clearly doesn't.
The detached outbuilding may equally for example be for plant (swimming pool pump, battery banks, gensets  etc) or a greenhouse, and they all have rules of their own that are significantly at odds with the rules for somewhere people sleep. And then supplies to caravans - where folk do sleep - are different again depending if they move or are static. TT earths for example.
Where it gets its supply from may affect the assumptions about voltage drop - which also may go negative for things that can generate, but the rules that apply to the two places are not identical - though they share a huge amount of common basis of course. That's why we have different extra chapters in BS7671 for various special situations and locations to highlight the differences.
Mike.

Hi Mike,

Thanks for your input. I understand your points about the specific rules for different types of outbuildings and structures, such as those for plant equipment, greenhouses, and caravans. While BS 7671 indeed contains chapters for various special situations and locations, our current discussion is centered around domestic garages within the same boundary as the main house.

The primary concern here is ensuring that all parts of an electrical installation within the same property adhere to the same safety standards. When a garage is electrically interconnected with the main house and within the same property boundary, it is essential to treat it with the same level of safety and compliance as the main domestic premises.

If there are specific sections in BS 7671 that you believe provide clear distinctions or additional guidance on this matter, I'd appreciate it if you could point them out. Our goal should be to ensure the highest standards of safety and compliance across all installations.

Let's continue this discussion with the aim of sharing knowledge and improving our understanding of electrical safety regulations.

Best regards, Gary Robert Jones

JIB registered Electrician, Grade Technician

Hi Gary. Q1.104 from WRAG. Can an insulated consumer unit or similar switchgear assembly complying with BS EN 61439-3 be installed in a detached outbuilding of a domestic (household) premises?

The primary concern here is ensuring that all parts of an electrical installation within the same property adhere to the same safety standards.

That's patently false - the electrical safety standards for a bathroom are significantly different to those for a bedroom within the same home for example (there's an entire section of differences in BS 7671 - Section 701). If two rooms within the same house have different standards, how does it follow that different rooms in different buildings serving differing purposes and containing differing environments must follow identical ones?

a detached garage is undoubtedly part of the premises

But not necessarily part of "domestic (household) premises" - when taken together with guidance issued by the IET and others at the time this regulation was introduced, it seems clear that detached outbuildings that are not normally lived in by members of the household were not intended to be covered by this regulation.

   - Andy.